Ark Royal vs Bismark

[delcyros]

I don't think one can say that Bismarck's TDS was "more effective" than the other TDS systems mentioned given that it was never seriously tested. The only torpedoes that struck Bismarck prior to her crippling hit in the stern ran too shallow and struck the armor belt near amidships greatly decreasing the blast effect. The stern hit, while a vulnerable place for any warship was particularily so for the class.

I seriously differ Your opinion. Why? First of all, BISMARCK TDS was seriously tested AND not defeated. It was tested by three torpedohits before the final battle, not two as You say (this is incorrect). One hit by VICTORIOUS airgroup hit the belt and was to shallow (no effect), two from ARK ROYALs airgroup also hit her. One on her stern as mentioned above and the other midships starboard in a proper depth well below the belt. The hit striked the TDS and it worked properly, thus no flooding inboards of the TDS mentioned (for some reasons I can´t explain, Bill Jurens is in possession of the ships flooding controll log, which was rescued by the ships damage engeneerer, handed over to the british. It will be published in Warships International)
Thus BISMARCK´s TDS defeated 18in aerial dropped torpedoes in action.
BUT, BISMARCK was also subject to torpedohits in her final battle. These were standart 21in ones from the cruisers, not the light aerial ones. Again no inwards flooding was caused by them and CAMERON´s diagnoses of the wreckage identified two of these impacts. Submergible remotely controlled drones filmed the adjacent spaces behind and while damage occured to the void and liquid cells, the strengthened bulkhead behind remained intact, thus wreckage analysis could verify survivors testimony in this case.
BISMARCK´s TDS also defeated 21in surface torpedoes.
Whether or not RODNEY hit her with a 23/4in torpedo could not be verified.
Her TDS was good but the whole system was good as well. A very large portion of the ships dwl was protected by the TDS and the ship had excellent compartimentation and the highest metacentric stability of all BB´s of ww2. That helps dealing with flooding.

Yamato, as mentioned faced far more powerful ordinance (TORPEX has twice the explosive power of the traditional TNT based torpedoes + the warheads were larger) and the torpedoes were set at the proper depth hitting under the armor belt. Under such conditions, Yamato still held up very well. Musashi in particular absorbed more torpedoes than any other battleship and remained afloat for hours thx to superb damage control. A Bismarck class would have surcombed from far less IMO.

YAMATO´s TDS failed when hit by 21in US non-TORPEX submarine torpedoes in 1943. And the system evidently failed at the joint between the face hardened and homogenious plates (this is a zone of weakness also for SOUTH DAKOTA and IOWA-classes). It also failed when hit by TORPEX augmented, but rather small aerial dropped torpedoes in 1945, there is no indication that it´s TDS defeated a single torpedo in the final battle. That she held up so well was in part caused by the sheer size of the hul (she was doomed to sink from less impacts anyway)l. MUSASHI did not suffered that many torpedoes as usually given credit for. Japanese survivors have been interrogated, the file can be found in the documents put forward by the US technical mission to Japan. I don´t remember the correct number (less than 10) but a case could be made that SCHARNHORST in 1943 at NORTH CAPE was subject to numerically more more powerful torpedoes (all of them were TORPEX augmented DD surface torpedoes) than was MUSASHI in 1944. MUSASHI´s damage controll was poor, she stayed afloat for some time because the damage of the one side partly levelled off the flooding she received from the other side. It was not superior damage controll but inferior tactics which helped the ship to stay afloat for hours. Her counterflooding abilities were considered inferior to deal with the situation.
Could a BISMARCK take this damage? Certainly not but in all cases mentioned (SCHARNHORST, YAMATO, MUSASHI) the ships would have sunk from fewer hit´s as well. BISMARCK has more protected space (as a part of total hullspace), better general damage controll facilities, more stability and thus more flooding tolerances. But it´s not a ship without weaknesses. It´s not a bad system as a whole. And the decision to revert to vertical strengthened bulkheads (after PBB´s and SCHARNHORST-classes inlcined ones) was a good one.

Littorio's system actually worked as designed, it might be noted too that her steering gear and props had superior redunancy and spacing built into the design vs. Bismarck's. A disabling hit in VV's stern was repaired at sea (granted, sea conditions were lesser) and the ship resumed under her own power to base.

LITTORIO would not take torpedoes very well. At first because the TDS failed in basically every instance, whenever tested and because LITTORIO´s had the for BB worst metacentric stability. It doesn´t help You when hit and heavily compromises any counterflooding attempts.

Prince of Wales TDS was well designed if basic but the spacing proved to be inadequate to contain the blast from a theoretical 1000llb charge. However, like Bismarck, what doomed her was a torpedo hit beyond her TDS system that damaged a prop and caused a runaway situation which loosened stuffing glands all the way back to one of her primary engine rooms causing extensive flooding. Poor damage control exaserbated the flooding as many WT hatches were left open.

The KGV class´s TDS suffered from a design defect. The TDS itselve is not poor, rather contrary, I rate it good. The problem lies in the gap between armour deck and TDS, there is one full deck level in height uncovered by the TDS and venting always occurs when hit by a torpedo. Thus a powerful enough torpedo could in theory bypass the TDS without defeating the strengthend bulkhead by flooding inboards via this gap and compromising watertightness by venting effects. Again, the whole class has a low metacentric stability, which doesn´t add any good at all.

Washington was not struck by torpedoes but her sister North Carolina was. This torpedo hit occured abreast turret #1 where the TDS was constrained by the narrowing hull shape and could not obtain full effectiveness. The Japanese torpedo was also far more powerful than the ones that struck Bismarck. Still, NC showed great resiliancey in being able to steam at speed out of the battlefield, her only major damages being her search radar. It was recommended that her #1 turret not fire under any circumstances save a dire emergency lest it weaken the bulkheads further.

It is even more terrible that the TDS failed there. While the explenation is correct, having an inbuildt weakness around the main magazines is simply not acceptable. The TDS is way to narrow where hit. The inclined bulkhead layout also are kind of questionable to me. They gave away in to many cases when tested.

RICHELIEU has a very promising TDS, it also narrows down (much more than BISMARCK but not as worse as NC) to the bow but this is counterbalanced by the gradually thicker strengthened bulkhead. The ship also has good metaceentric stability. A good layout. The problem I see in the whole system is that only 8 out of 18 compartements are protected by the TDS, so in theory You may end up sinking the ship without needing to defeat the ship´s TDS in the first place...

 

[Juha]

Delcyros
sorry to say, also the twins' (Scharnhorst and Gneisenau) TDS suffered a design defect, look what happened on 8 June 40 when Scharnhorst got one torpedo hit from Acasta, 2500tons water in, C-turret inoperative 48 KIA.

Juha

 

[delcyros]

Delcyros
sorry to say, also the twins' (Scharnhorst and Gneisenau) TDS suffered a design defect, look what happened on 8 June 40 when Scharnhorst got one torpedo hit from Acasta, 2500tons water in, C-turret inoperative 48 KIA.

Juha

That´s correct. The strengthened bulkhead worked as designed and flexed but the inclination of it caused pressure distribution problems and the joint failed. Similar failures are reported from very many inclined bulkhead layouts. Following cassion tests in 1935, the BISMARCK class reverted to the conventional but effective vertical bulkhead layout after the experimentation in the DEUTSCHLAND class PBB´s and the twins. The inclined layout is way better against projectiles but worse when overpressure bubbles are formed.
The BM-class does not share this design defect with the twins.

 

[Juha]

Delcyros
I agree, it is also my understanding that the main reason of the failure of the TDS of Scharhorst on that day was that the main torpedo bulkhead was inclined. Also the lines of twins were rather fine because of the demands of high speed and so near ends of TDS its depth was a bit smaller than what the designers would have put in beamier ship. In BM-class the greater beam allowed vertical bulkhead with adequate depth of TDS.

Juha

 

[Nikademus]

I seriously differ Your opinion. Why? First of all, BISMARCK TDS was seriously tested AND not defeated. It was tested by three torpedohits before the final battle, not two as You say (this is incorrect).

Hi,

Designers can't deploy a fully effective TDS either at the stern or bow of a warship as the hull is simply too narrow to provide the same level of protection as it can amidships. I would be doing the Bismarck class a dis-service if i were to use the stern torpedo hit as an example of a "failed" TDS. It is not remiss however to point out that Bismarck's rudder and propulsion setup in the stern was a point of weakness in the design. Hence up to the point of Bismarck's crippling, she had only taken two torpedo hits in the area protected by her TDS. It was also a fair and valid point to refer to a similar situation that impacted the Littorio class, a situation in which the Italian ship proved better able to handle such a hit.

One hit by VICTORIOUS airgroup hit the belt and was to shallow (no effect), two from ARK ROYALs airgroup also hit her. One on her stern as mentioned above and the other midships starboard in a proper depth well below the belt. The hit striked the TDS and it worked properly, thus no flooding inboards of the TDS mentioned (for some reasons I can´t explain, Bill Jurens is in possession of the ships flooding controll log, which was rescued by the ships damage engeneerer, handed over to the british. It will be published in Warships International)
Thus BISMARCK´s TDS defeated 18in aerial dropped torpedoes in action.

According to research by William Garzke, the 2nd torpedo hit did result in tearing damage to the torpedo bulkhead's welding seams resulting in minor progressive flooding beyond it. Based on what appears to be your definition of "success" for a TDS, this would represent a "failure". Overall though i agree, the TDS did perform adequately up to this point. I did not comment on the subsequent torpedo salvoes at Bismarck because they occured after the action vs. KGV and Rodney at that point they were firing at a wrecked hulk, already severely damaged. Still, Garzke and Dunn consider the damage caused by these hits to have been substantial in the sinking of the ship.

BUT, BISMARCK was also subject to torpedohits in her final battle. These were standart 21in ones from the cruisers, not the light aerial ones. Again no inwards flooding was caused by them and CAMERON´s diagnoses of the wreckage identified two of these impacts. Submergible remotely controlled drones filmed the adjacent spaces behind and while damage occured to the void and liquid cells, the strengthened bulkhead behind remained intact, thus wreckage analysis could verify survivors testimony in this case.
BISMARCK´s TDS also defeated 21in surface torpedoes.

This has not been conclusively determined. "Cameron" is not a naval design expert nor was he able to full examine all of Bismarck's damage. The Wikipedia article I assume your drawing this from cites Cameron's opinion based on the images he was able to view makes for good fodder to reintroduce the theory that Bismarck's citadel was impenetrable but is ultimately unconvincing. In contradiction to this Gazarke's analysis, taking into account these recent expeditions, actually suggests that Bismarck was more vulnerable to torpedoes than shellfire.

Her TDS was good but the whole system was good as well. A very large portion of the ships dwl was protected by the TDS and the ship had excellent compartimentation and the highest metacentric stability of all BB´s of ww2. That helps dealing with flooding.

Torpedo defensive "coverage" is fairly standard for post WW1 battleship class vessels. I agree Bismarck's compartmentalization was good and was similar in respect to that of the modern USN designs in that it precluded the use of a central longitude bulkhead separating port and starboard spaces greatly reducing the threat from capsizing.

I think you meant to say "Metacentric Height" (GM), not "metacentric stability". Your correct in that it was highest in Bismarck. This was not necessarily a good thing. The Germans favored a high GM to provide stability in the face of battle damage but some naval design authors like Garzke consider the GM of the class to have been too high resulting in over-stiffness which caused some unpleasant rolling characteristics and at worst, would impede her gunnery efficiency. Either way this has little to do with a discussion regarding the ship's TDS. GM concerns designers in regards to overall stability irregardless of the TDS specifics and is also equally of concern for creating a good gunnery platform. British designers were well aware of this and favored a lower GM in order to create a better gunnery platform.

YAMATO´s TDS failed when hit by 21in US non-TORPEX submarine torpedoes in 1943. And the system evidently failed at the joint between the face hardened and homogenious plates (this is a zone of weakness also for SOUTH DAKOTA and IOWA-classes).

Yamato's TDS proved more vulnerable than the designers planned for due to a weakness in the joint between the primary belt armor and the torpedo bulkhead. However what you fail to mention is that the significance of this weakness is dependant on location of torpedo hits and will not factor greatly (or at all) in all situations. Your claim that every torpedo hit resulted in "TDS failure" is inaccurate and vague. I have detailed info on both ship's demise. I would be interested in seeing your data on these torpedo hits.
Further, the connection with SODAK and Iowa's TDS is not accurate because the designs were not identical to Yamato nor was the metallurgy issue the same. There was no 'weak joint' as was the case with Yamato.

The two USN designs were constrained by the naval treaties in place at the time and the designers emphasis was on defeating 16 inch shells. Hence, the prior 5 layer elastic TDS defense of earlier 'Standard' type USN BB's was dropped in favor of a more ballistically rigid defense scheme designed to counter diving heavy shells.

Caisson tests later revealed that this was not as ideal vs. torpedo hits vs the system used in North Carolina but partial compensation was effected by adjusting the liquid load/void arrangement of the TDS. In the case of SoDak, torpedo damage would remain a concern as being a 35k treaty battleship of cramped design (to counter 16 inch gunfire on a fixed displacement), she was more vulnerable. Iowa was less vulnerable given her increased displacement and less cramped design as North Carolina. To reitterate, North Carolina did not have the integrated inclined internal belt/TDS interior most bulkhead you are alluding too and criticizing. (Note as well that the internal torpedo bulkhead attached to the internal belt was only one of multiple bulkheads)

It also failed when hit by TORPEX augmented, but rather small aerial dropped torpedoes in 1945, there is no indication that it´s TDS defeated a single torpedo in the final battle.
That she held up so well was in part caused by the sheer size of the hul (she was doomed to sink from less impacts anyway)l. MUSASHI did not suffered that many torpedoes as usually given credit for. Japanese survivors have been interrogated, the file can be found in the documents put forward by the US technical mission to Japan. I don´t remember the correct number (less than 10)

I would love to see this evidence. In the meantime information I have suggests at least 11 torpedo hits + 10 bomb hits and 6 near misses, some of which caused flooding for Musashi. Yamato took 13 torpedo hits, 8 bomb hits and an unknown number of near misses. Citing the size of the hull alone is not justified based on the analysis i have read on both ship's demise. These were against torpedoes with a TNT equivalent of at least 900lbs.

(continued)

 

[Nikademus]

but a case could be made that SCHARNHORST in 1943 at NORTH CAPE was subject to numerically more more powerful torpedoes (all of them were TORPEX augmented DD surface torpedoes) than was MUSASHI in 1944. MUSASHI´s damage controll was poor, she stayed afloat for some time because the damage of the one side partly levelled off the flooding she received from the other side. It was not superior damage controll but inferior tactics which helped the ship to stay afloat for hours. Her counterflooding abilities were considered inferior to deal with the situation.

Please make the case.

Could a BISMARCK take this damage? Certainly not but in all cases mentioned (SCHARNHORST, YAMATO, MUSASHI) the ships would have sunk from fewer hit´s as well. BISMARCK has more protected space (as a part of total hullspace), better general damage controll facilities, more stability and thus more flooding tolerances. But it´s not a ship without weaknesses. It´s not a bad system as a whole. And the decision to revert to vertical strengthened bulkheads (after PBB´s and SCHARNHORST-classes inlcined ones) was a good one.

I'm not sure i understand what you mean by "more protected space" Bismarck's armor scheme was based on an older incremental type armor scheme that covered more of the ship with areas of light and medium armor on the idea that small and medium caliber shell threats had to be accounted for as well as heavy shells. In the closer WWI and pre-WWI combat environments this was justified but as shell technology progressed it became increasingly difficult to protect the bulk of a ship from the heaviest shells due to weight constrictions. Worse, medium and light armor could exaserbate a situation vs. heavy BB shells because the armor is too thin to prevent penetration but is thick enough to initiate fuse action ensuring that the shell detonates inside the ship vs. passing through the hull. This factor was recently determined to have had substanial impact on the loss/disablement of the HIJMS Kirishima at Third Guadalcanal when facing the modern 16inch shells from USS Washington. Here the ship's older "Incremental armor design" led to multiple detonations of 16 ship shells aboard ship that in an All or Nothing scheme would have caused less damage because the shell would have passed through the unarmored sections without exploding. (As was the case with the bulk of the shellfire that struck South Dakota in that same action)

The solution to the challenge of bigger, more effective heavy BB shellfire, first deployed by the USN during the Dreadnought Era was the "All or Nothing" armor scheme designed to give maximum protection against BB primary armaments at the expanded ranges expected in WW1 and post WW1 combat. This scheme embraced the idea that only the most vital parts of a warship would be armored and those sections would receive the maximum thickness possible to protect against heavy shellfire. This meant that less vital areas (who's loss/flooding would not endanger the ship, usually outside the protected citidel) had no armor protection or at most splinter protection. Yamato (and all other modern BB designs, except in the case of Germany) embraced this weight saving technique in order to maximize protection against battleship heavy shells.

So to say Bismarck had "more protected hull space" doesn't mean all that much. I don't agree that Bismarck had superior damage control based on evidence I've seen and as for the "stability" issue, I'd wager that Bismarck would be a tough ship to sink outright vs gunfire as demonstrated (the converse being that in terms of disabling her, she proved quick to take out...part of the price she paid for having the older deck armor scheme that emphasised vertical protection at shorter gun ranges with the primary armor deck placed lower than in other WW2 BB's so that it's slopes could reinforce the armor belt)

Against torpedoes, as mentioned, Gazarke's work suggests the ship was vulnerable to torpedo damage. I seriously doubt the class could take as much torpedo damage as a Yamato given the warhead sizes she faced during her last battle. (equivalent to 900lb TNT)

If you want to talk most protected buoyancy/hull protection vs BB shellfire, you'll find that the KGV class had top marks in that regards.

LITTORIO would not take torpedoes very well. At first because the TDS failed in basically every instance, whenever tested and because LITTORIO´s had the for BB worst metacentric stability. It doesn´t help You when hit and heavily compromises any counterflooding attempts.

I beg to differ on the failed every time instance though if you have some specific info on the subject I'd be interested in seeing it. You keep mentioning GM (Metacentric Height) in your analysis of side protection systems.....I respectfully suggest though that you read up on the subject of GM (Metacentric Height) before making any more of these assertions.

The KGV class´s TDS suffered from a design defect. The TDS itself is not poor, rather contrary, I rate it good. The problem lies in the gap between armor deck and TDS, there is one full deck level in height uncovered by the TDS and venting always occurs when hit by a torpedo. Thus a powerful enough torpedo could in theory bypass the TDS without defeating the strengthend bulkhead by flooding inboards via this gap and compromising watertightness by venting effects. Again, the whole class has a low metacentric stability, which doesn´t add any good at all.

KGV's TDS had several design flaws which indicated that the theoretical 1000lb charge resistance was overrated. Battle experience did indicate that the protection system was not deep enough if the deck above the TDS was ruptured resulting in flooding in those less compartmentalized spaces. Yes, torpedo blasts always "Vent" but not always in any one direction or predictably. A variety of factors impact this. Various studies on PoW's action do not all agree or can fully determine exact damage in all cases. It would appear that the SPS functioned adequately in some cases, in others not. Further, cumulative damage from prior attacks also factored into the reduction of the SPS's effectiveness as did crew damage control mistakes. Irregardless, the crippling hit occurred beyond the SPS but in the stern section.

It [NORTH CAROLINA] is even more terrible that the TDS failed there. While the explanation is correct, having an inbuildt weakness around the main magazines is simply not acceptable. The TDS is way to narrow where hit. The inclined bulkhead layout also are kind of questionable to me. They gave away in to many cases when tested.

I'm not sure what "inbuilt weakness" you are referring too. Unless you are designing a battleship like a modern supertanker, it is impossible to provide the same space requirements of a TDS system abreast the forward most turret vs. amidships. This is simple fact. Bismarck was no different here. I'm not sure what test cases you are referring too. The USN did perform Caisson tests on the SoDak and Iowa which had a different internal SPS but i'm not aware of such for North Carolina. Can you provide some details?

In fairness to your point, it is true that the torpedo hit revealed weaknesses in modern USN TDS systems. This was acknowledged by BeauOrd. However, it is also true that USN designers, unlike the KM designers were far more constrained in what they could do due to the Washington Naval Treaty limiting BB displacement to 35,000 tons Standard, the Germans were able to ignore displacement limits and greatly inflate the size of the Bismarck to accomidate their cumulative requirements. THe USN (and UK and French), Faced with such steep windfalls they had to balance balistic protection vs. torpedo protection and compromises and sophisticated approaches were attempted. Further, as documented in Garzke and Dunn's work "United States Battleships 1935-1992" with supporting material from Norman Friedman's "US Battleships", the torpedo hit suffered by the North Carolina occurred at the most vulnerable location of the TDS, where the hull constricted it's depth. Still further, the torpedo warhead was more than double the strength of the warheads used against Bismarck, equivalent to 960lbs of TNT. This was far in excess of the TNT load the class was designed to face at the optimal depth of it's TDS, and more than that designed into Bismarck. All in all BeauOrd was not unhappy with NC's performance in 42. The ship, despite heavy structural damage was able to continue steaming at high speed (for a short period) and remained combat viable with restrictions. This after absorbing a charge greater than the 700LB theoretical she was designed to absorb at her SPS's optimum point much less where the actual hit occured.

RICHELIEU has a very promising TDS, it also narrows down (much more than BISMARCK but not as worse as NC) to the bow but this is counterbalanced by the gradually thicker strengthened bulkhead. The ship also has good metaceentric stability. A good layout. The problem I see in the whole system is that only 8 out of 18 compartements are protected by the TDS, so in theory You may end up sinking the ship without needing to defeat the ship´s TDS in the first place...

Richelieu arguably had the best designed TDS of all the WW2 BB designs. Again I'm not sure what you mean by "only 8 of 18 compartments" protected by the side protection system. The citadel (primary compartments...including magazine and propulsion spaces) were protected by the side protection system as in all other WW2 battleships. I think you are again confusing the nature of the "All or Nothing" protection scheme employed by all major naval powers post WW1 with the exception of Germany.

 

[RCAFson]

KGV's TDS had several design flaws which indicated that the theoretical 1000lb charge resistance was overrated.

From what I've read it seems that the KGV TDS was tested full scale with an actual 1000lb charge. The TDS worked as planned and prevented a breach of the inner bulkhead.

 

[skeeter]

Just my two cents worth. Bismark was shipping water through a shell hit and was running down at the bows, but I do not know if it was from the Prince of Wales or the Hood. She had to reduce speed and in so doing, this aided in the effort to find her in time before she came within range of a defending umbrella of German aircraft. Didn't the Ark Royal embark Blackburn Skua dive bombers at the time? These could carry up to five hundred pound bombs. Would five hundred pounders have been able to penetrate her armored deck? I don't know about the torpedos of the time in question, but I do know that nowadays, they set them to go off under the hull, cracking it and breaking it effectively in two.

 

[Nikademus]

From what I've read it seems that the KGV TDS was tested full scale with an actual 1000lb charge. The TDS worked as planned and prevented a breach of the inner bulkhead.

Full details on Job #74, the pre-build testing of the KGV classes Side Protection System do not appear to be available according to naval designer/historian D.K. Brown but the gist of it was yes, this test series, using a scale mock appeared to indicate that the SPS would withstand up to a 1000lb charge of TNT "in theory." The scale mockup was 72ft long and 50ft deep with internal compartments fitted out to BB and CA standards of the time.

The first series of trials for #74 involved a sandwich system on one side and a modified d'Eyncourt bulge on the other. Overall beam was 100feet. Sandwhich was 20feet deep to the holding bulkhead which were of two thicknesses of 35lb plate. Outboard compartment was of air, to allow venting from gasses to expand freely. Next was a liquid layer (water, later oil) to spread pressure load evenly and stop fragments from the torpedo and thick bulkhead + outer hull. It was 'expected' that the thick bulkhead would distort and leak so a watertight compartment was provided inboard to help contain this. A 1000lb charge was exploded against the mockup resulting in a hole 25ft x 16ft in the outer plating. It destroyed the two intermediate bulkheads a length of 36 feet and deflected the main protective bulkhead 18 inches inward which resulted in some damage to the innermost bulkhead. The test vs. the bulge was less successful, the main bulkhead being ruptured. A later trial using modified holding bulkheads failed through the welds. Overall though the test seemed to validate the sandwich design.
[Source: D.K. Brown "Nelson to Vanguard: warship design and development 1923-45]

Unfortunately the test of real combat indicated that the SPS performance was less than what was indicated in Job 74. (The torpedo warheads used by the G3M/G4M force was 330 lbs for example) Brown notes that a primary difference between test and combat came from the damage due to the hits on the prop shafts which resulted in the opening up of a large underwater volume of the ship to the sea resulting in severe flooding.

There were three hits on the SPS itself. A port side hit near Frame 206 might have caused flooding in the aux machinary space but it was also possible it was a result of the shaft damage from the prior attack. The protection at Frame 236 "worked well" [Brown], but because the void spaces had been filled as a counterflooding measure, the system could not prevent flooding following the hit.
According to Brown, Job 74 appeared to have overvalued the system (aka 1000lb charge resistance) but should in theory have contained 330lb charges well enough. (assuming a fully intact system) The prop hits of course, which did the fatal damage fell outside the SPS protection scheme.

 

[Nikademus]

Just my two cents worth. Bismark was shipping water through a shell hit and was running down at the bows, but I do not know if it was from the Prince of Wales or the Hood. She had to reduce speed and in so doing, this aided in the effort to find her in time before she came within range of a defending umbrella of German aircraft. Didn't the Ark Royal embark Blackburn Skua dive bombers at the time? These could carry up to five hundred pound bombs. Would five hundred pounders have been able to penetrate her armored deck? I don't know about the torpedos of the time in question, but I do know that nowadays, they set them to go off under the hull, cracking it and breaking it effectively in two.

Hit came from Prince of Wales. 500lb bombs would not have done much against Bismarck. (In terms of stopping or sinking her) The ship employed a bomb armor deck above the main armor deck at a thickness of 50mm. While this scheme made the class vulnerable to plunging shellfire, in the case of bombs like a 500lber it would likely initiate fuse action on a 500lb if it didn't stop it outright, resulting in detonation of the weapon on reaching the main armor deck which was 145mm thick over the magazine spaces and 130mm thick over the Machinary spaces.

 

[pinsog]

How many classes of torpedoes did the British have? 18 inch aerial and how many more? How much did each weigh? How much weight was the Swordfish capable of carrying?

 

[delcyros]

There were multiple torpedo sizes in service by the british as of ww2. But FAA bombers usually carried 18in ones of different marks, such as the Mk XII introduced 1937 with a 388lbs TNT charge, the Mk XIV introduced 1938 with 375 lbs TNT charge. Later on, airplanes dropped TORPEX augmented torpedoes with greatly increased warheads, the MK XV (introduced 1942) had 545 lbs TORPEX.

Nikedamius, please feel free to continue our part of the discussion on this thread:

http://www.ww2aircraft.net/forum/ww2-general/best-world-war-two-warships-3592-48.html

I will respond, but am away from my books now, so be patient with the answer.

best regards,
delc

 

[RCAFson]

Hit came from Prince of Wales. 500lb bombs would not have done much against Bismarck. (In terms of stopping or sinking her) The ship employed a bomb armor deck above the main armor deck at a thickness of 50mm. While this scheme made the class vulnerable to plunging shellfire, in the case of bombs like a 500lber it would likely initiate fuse action on a 500lb if it didn't stop it outright, resulting in detonation of the weapon on reaching the main armor deck which was 145mm thick over the magazine spaces and 130mm thick over the Machinary spaces.

500lb bombs alone would have a tough time sinking Bismarck, but in combination with torpedo hits could have caused a fatal combination of damage. Torpedo hits could reduce the freeboard to allow flooding via 500lb bomb created holes in the deck or ship's side.

 

[parsifal]

500 lb bombs wont sink a capital ship, but they can cause a lot of damage to the upper works, and reduce the combat efficiency of the ship, to say nothing of inflicting casualties on the AA crews and any other crew working on the upper deck. A ship is just an inanimate pile of metal, but it is crewed by human beings, with all the frailities that goes with that. If the ship is taking damage from torpedo hits, and also suffering damage topside, ther is a natural tendency for the crew to at least become panicky, excercise poor judgment to damage control issues, and the like. This happens to every ship under sustained attack, especially when under attack from multiple threats. I believe the crew of the bismark suffered from that problem during her last fight....at the end the crew had no fight left in them. So dropping 500 lb bombs on a ship like the bismark is far from a waste of time....in my opinion.

 

[Nikademus]

How many classes of torpedoes did the British have? 18 inch aerial and how many more? How much did each weigh? How much weight was the Swordfish capable of carrying?

alot at the time of the Bismarck battle. More still later in the war.

24.5" Mk 1 - charge 743LB. Carried by BB Rodney.

21" Mk 2 - charge 400lb An older WWI design.

21" Mk 4 - charge 445lb another WWI design

21" Mk 5 - charge similar to Mk 4. WWI design

21" Mk 7 - charge 740lb. Post WWI design, originally an O2 enriched design, later converted to compressed air only. (Per Cambell, 198 expended up to 9/44 during WW2

**

18" Mk 7 pre-WWI design - 320lb charge

18" Mk 8 pre WWI design - similar to Mk 7. originally designed for sub use, converted to aircraft weapon

18" Mk 11 - charge 465lb

Torpedoes built 1939+

21" Mk 9 - charge 750lb

21" Mk 10 - charge 661lb

21" Mk 11 - charge 710lb

18" Mk 12 -charge 388lb

Swordfish carried 18 inch types of torpedoes. The 388lb Mk-12 was typical of the ordinance carried by the type. Late in the war an improved Mk 12 was introduced with a warhead of 545lb TORPEX

 

[Kurfürst]

Hi Nikademus,


Rather good discussion so far!

Please make the case.

I'm not sure i understand what you mean by "more protected space" Bismarck's armor scheme was based on an older incremental type armor scheme that covered more of the ship with areas of light and medium armor on the idea that small and medium caliber shell threats had to be accounted for as well as heavy shells. In the closer WWI and pre-WWI combat environments this was justified but as shell technology progressed it became increasingly difficult to protect the bulk of a ship from the heaviest shells due to weight constrictions. Worse, medium and light armor could exaserbate a situation vs. heavy BB shells because the armor is too thin to prevent penetration but is thick enough to initiate fuse action ensuring that the shell detonates inside the ship vs. passing through the hull. ... Richelieu arguably had the best designed TDS of all the WW2 BB designs. Again I'm not sure what you mean by "only 8 of 18 compartments" protected by the side protection system. The citadel (primary compartments...including magazine and propulsion spaces) were protected by the side protection system as in all other WW2 battleships. I think you are again confusing the nature of the "All or Nothing" protection scheme employed by all major naval powers post WW1 with the exception of Germany.

I think he means the lenght of the citadel on the Bismarck vs. the other Treaty Battleships. Bismarcks citadel and TDS run at something like 70% of the hull, protecting a lot more buoyancy than typically found on other Battleships (typically 50-60%). Ie. indeed Richelieu's protection was extremely good, both from the ballistic and the anti torpedo POV, (I too very much like the class) where it extended protected the ship. But while the vitals were offered good protection, it came at the price of not offering any protection to much of the ship, and this would lead to increased flooding at the soft ends of the ship when hits were suffered in that region.

German battle experience of World War I at Skagerrak indicated the dangers of this with the loss of the battlecruiser Lützow, which was lost to progressive flooding due to large caliber shell hits to the bow while it tried to reach back to base, albeit it was slow enough that most of the crew could be saved - even when both magazines and machinery was intact. The lesson was clear, and both the Scharnhorst and Bismarck classes featured long and extensives citadels covering 70% of the ship hull, and lot of reserve buoyancy to prevent this happening. The same goes to Yamato classes, for example, that was lost to this reason - even though the ship had extraordinary protection in its citadel, it didn't help when shells and torpedoes hit outside it, and there was a larger chance of this happening. You can't just expect that shells will do the courtesy of always hitting your protected areas, its a bit akin to expect the enemy in land war to always manouver into your killzones, rather than trying to flank you. The vitals safe is important, but if the ship is lost to flooding in the meantime it can prove somewhat irrelevant.

Now, regarding the "old incremental type of armor", with lighter plating to protect against small and medium caliber hits - I guess here you refer to the 145mm upper side belt on Bismarck, in the same fashion as on the Bayern class of WW1 - it certainly worth to look at how German capital ships evolved from the Scharnhorst to the Bismarck. It wasn't just taking the Bayern and using its scheme for Bismarck.

On Scharnhorst they completely took a step aside from the WW1 designs, using only a 50 mm upper side belt against small caliber shellfire, and a rather thick main belt of 350mm, and also, triple turrets. On Bismarck they changed both of these features, and it was certainly no accident. Actually the use of triple thickness upper side belt on the Bismarck was a very good feature, even saving weight for added protection.

It allowed for example shaving off some 100 mm from all four barbettes, which could be now just 220mm thick below the armored top deck, since even if shells passed through the 145mm upper side belt (not to mention the main belt) had no chance of penetrating the barbettes inside the ship except for suicidal distances - certainly a lot better protection than a single 320mm (iirc) barbette would offeron Scharnhorst. The fact that the 145mm belt also offered protection up to heavy cruiser sized guns and smaller for the whole citadel (fires!) and augmented the protection of the main armored deck was an added bonus.

Regarding the closer combat ranges of World War I, it is of course true, and most Treaty battleships protection scheme was optimized for much longer combat ranges with thick main decks. On the other hand, if you look at the practical combat ranges found in World War II (10 - 26 000 yards), and compare them to the Immunity Zones of the various designs, you will find that aside from Yamato, it is the Bismarcks that find themselves in a most convinient situation: their vertical ballistic protection was the best of the lot, and their admittedly weaker horizontal protection was just good enough for these ranges. It certainly looks to me that German naval designers got it fairly what the optimal IZs were: just about anywhere between point blank and out to 26-28 000 yards, the only way to KO a Bismarck class was to get a soft kill on it, which was not particularly easy either due to generously protected bouyancy, a large and well divided hull, and the redundancy offered for the armament (ie. four main turrets, three directors vs the usual three and two). And that redundancy is important, I always felt that the other designs would, somewhat naively expect that naval combat, with shells of size of a small car in the air at supersonic speeds, can be somehow fought while remaining nice and clean, and without a scratch. On the contrary I think its a bloody business, damage to the ship WILL occur, and it is going to be messy when it does. I think its a more realistic approach to accept the inevitable, but make sure that when it occurs, it effects the ship overall combat capability the least. That's my major grief with the Richeliue's, whose design and looks I like otherwise very much - what if a turret just jams? What if somebody just pops out the fog at 12 000 yards distance and begins to fire? What if the bow and stern are flooding, and the upper works is on fire from small caliber hits..? What if the tactical circumstances are just unfavourable, ie. you would need to fire to targets to the stern? IMHO the problem with such designs is that they expect that everything will happen just the way the designers wanted them to happen, ie. ideal tactical situation that suits the ship, with shells landing nicely where protection is offered against them. But few battle plan survives the first contact with the enemy..

 

[Nikademus]

I think he means the length of the citadel on the Bismarck vs. the other Treaty
Battleships. Bismarcks citadel and TDS run at something like 70% of the hull,
protecting a lot more buoyancy than typically found on other Battleships
(typically 50-60%).

Hi,

Bismarck's heavy belt armor covered 68% of her hull at the waterline which compared favorably to other designs (constrained by Treaty) at the time she was being built. It did not reflect any particular area of superiority however. The point is that it's standard in WWII BB's to protect the vital area of the ship (usually called the "citadel"), which covers the ship's primary armament and machinery spaces. Where things can vary more is depth of protection and in armor thickness. These were areas of strength of the KGV class for example, which had a deep and uniform belt of BB level protection topped by her primary armor deck (placed higher as was general practice except in the case Germany where the deck remained lower slung in order to reinforce the belt). The only variance in this belt was that thickness was greater abreast magazine spaces vs. machinery spaces. Thus KGV's "protected buoyancy" (against heavy shellfire) was greatest in comparison to other BB's. In the case of Yamato (oft mentioned here), her designers placed great care in regards stability and subdivision in the face of damage. The citadel was relatively compact as part of a requirement to maximize armor protection. The ship was designed to retain positive longitudinal stability even if the bow and stern sections were flooded. Ultimately length of armor belt is irrelevant if the belt is vulnerable to the shellfire faced from a primary opponent type.

Ie. indeed Richelieu's protection was extremely good, both
from the ballistic and the anti torpedo POV, (I too very much like the class)
<I>where it extended protected the ship</I>. But while the vitals were offered
good protection, it came at the price of not offering any protection to much of
the ship, and this would lead to increased flooding at the soft ends of the ship
when hits were suffered in that region.

This is a basic concept of an All or Nothing protection scheme. The idea is to protect only the critical areas of a battleship and that with the thickest armor possible, leaving the non-critical areas unprotected. The ends of a BB, along with light superstructures, if damaged would not threaten the safety of the ship. Richelieu's citadel was intentionally concentrated in order to increase protection against heavy shellfire.

<BR><BR>German battle experience of
World War I at Skagerrak indicated the dangers of this with the loss of the
battlecruiser Lützow, which was lost to progressive flooding due to large
caliber shell hits to the bow while it tried to reach back to base, albeit it
was slow enough that most of the crew could be saved - even when both magazines
and machinery was intact.

Lutzow's condition was caused by a number of factors. The progressive flooding was a result both of shell damage and due to many piercings of critical bulkheads which negated somewhat the otherwise very good sub-division of the ship and exacerbated damage control efforts. Another factor in Lutzow's loss was the large bow torpedo flat, a typical feature of WWI era German capital ships. This large space, if compromised would reduced bouyancy reserves in the bow area. Lutzow eventually was scuttled because the ship's trim had been so radically altered by the forward flooding that movement was next to impossible but she was not in danger of actual sinking up to that point. This decision to scuttle is questioned in some quarters as the ship's buoyancy reserves were far from exhausted and the ship (arguably) could have been saved. Had Lutzow's bow area been unprotected, the shells would have had a greater chance of passing through the narrow hull section without detonation. Instead, the medium/light armors ensured detonation increasing structural damage and contributing to the loss of the ship. This makes Lutzow a case demonstrating how medium and light armors can be detrimental to a warship when struck by heavy shells.

The lesson was clear, and both the Scharnhorst and
Bismarck classes featured long and extensives citadels covering 70% of the ship
hull, and lot of reserve buoyancy to prevent this happening.

Citadel length is determined in part by the size of the machinery and primary armament, and is also influenced by the hull form requirements for speed. Finally armor thickness requirements impacts Citadel length. "Reserve Buoyancy" is a product of the overall armor scheme's depth as well as its length, not just the armor belt.

(continued)

 

[Nikademus]

The same goes to
Yamato classes, for example, that was lost to this reason - even though the ship
had extraordinary protection in its citadel, it didn't help when shells and
torpedoes hit outside it,

Both ships of the Yamato class suffered fatal damage to their vitals.

. Actually the use of triple thickness upper side belt
on the Bismarck was a very good feature, even saving weight for added
protection.

I wouldn't agree with that. The weight of this multi belt system resulted in reduced thickness to the primary armor belt. Eliminate the middle/upper belt and one can maximize the primary belt protecting the ship's waterline and increase its depth. The German designers compensated for this somewhat by keeping the armor deck low in a turtleback design reflecting their view that a typical North Sea engagement would be relatively close. The slopes reinforced the belt making the ship very resistant to veridical fire. The cost of the lower deck armor was more exposure of topside systems to damage and reduced protected buoyancy in the event of major flood damage. Hood, a WWI vintage design suffered a similar weakness. She had 3 belts, heavy, medium and light on the same theory that closer ranged combat required greater full hull coverage against a variety of ordinances. As a result of this requirement, her heavy belt was shallow and modern convention holds that the fatal hit inflicted on her was caused by a heavy shell penetrating her mid-belt (7") which was fully vulnerable to 15inch shellfire. The UK was aware of Hood's weakness but the ship was too advanced to alter and instead of a single deep belt of maximum thickness capped by a singular strong armor deck, she retained the incremental scheme of her predecessors. Unmodified, it proved fatal to her during WWII.

<The fact that the 145mm belt also
offered protection up to heavy cruiser sized guns and smaller for the whole
citadel (fires!) and augmented the protection of the main armored deck was an
added bonus.

The 145mm belt was employed to keep medium caliber shells from entering the spaces above the battery deck (protecting uptakes and ammunition handling spaces). The designers were convinced that potential close encounters with DD's and cruisers made this provision necessary (and thus absorbed critical weight that might have been put into the primary belt.) The upper belt did not prove to be proof against UK 152mm and 203mm shellfire.

<BR><BR>Regarding the closer combat ranges of World War I, it is of
course true, and most Treaty battleships protection scheme was optimized for
much longer combat ranges with thick main decks. On the other hand, if you look
at the practical combat ranges found in World War II (10 - 26 000 yards), and
compare them to the Immunity Zones of the various designs, you will find that
aside from Yamato, it is the Bismarcks that find themselves in a most convinient
situation: their vertical ballistic protection was the best of the lot, and
their admittedly weaker horizontal protection was just<I> good enough</I> for
these ranges.

Bismarck's protection scheme made her very resistant to close in vertical fire at the expense of greater vulnerability at expanded ranges to plunging fire and helps explain why she stayed defiantly afloat against the short range fire she was subjected too. An additional con of this was that close in fire deflecting off the lower armor deck slopes would increase topside damage and contribute to the ship being made combat ineffective, as occurred. The primary armament proved suprisingly vulnerable to heavy BB shellfire; One 16in hit took out half of Bismarck's primary armament. As a class the ships proved very tough, but the tradeoffs were evident as well.

It certainly looks to me that German naval designers got it fairly
what the optimal IZs were: just about anywhere between point blank and out to
26-28 000 yards, the only way to KO a Bismarck class was to get a soft kill on
it, which was not particularly easy either due to generously protected buoyancy,
a large and well divided hull, and the redundancy offered for the armament

Bismarck was disabled rather quickly by Rodney and KGV. She proved difficult to sink however which has led to a long standing and silly argument about "Sunk vs Scuttled." To me it's irrelevant....the ship was stopped and wrecked. The USN for example, couldn't have cared less whether or not Haruna or Kirishima were scuttled vs. sunk. The only thing that mattered was that the ships sank. As mentioned, light/medium armor does not provide "protected buoyancy" against heavy shellfire or medium shellfire on some cases. Bismarck's armament was driven primary by what the Germans considered the optimal organizational effect a traditional four turret (2 guns each) offers. The penalty paid here was increased weight which resulted in a longer and heavier citadel. Had a three gun/three turret armament been opted for, weight would have been saved, an additional gun barrel would have been obtained and the primary belt armor could have been shortened, saving more weight allowing it to be thickened. The "large hull" was a product of the rather bloated nature of the design which continually increased in size as requirements were piled onto it. The German designers could do this because they were not contrained by the Washington Treaty. The Italians were also guilty of flagerantly exceeding these limits.

 

[pinsog]

alot at the time of the Bismarck battle. More still later in the war.

24.5" Mk 1 - charge 743LB. Carried by BB Rodney.

21" Mk 2 - charge 400lb An older WWI design.

21" Mk 4 - charge 445lb another WWI design

21" Mk 5 - charge similar to Mk 4. WWI design

21" Mk 7 - charge 740lb. Post WWI design, originally an O2 enriched design, later converted to compressed air only. (Per Cambell, 198 expended up to 9/44 during WW2

**

18" Mk 7 pre-WWI design - 320lb charge

18" Mk 8 pre WWI design - similar to Mk 7. originally designed for sub use, converted to aircraft weapon

18" Mk 11 - charge 465lb

Torpedoes built 1939+

21" Mk 9 - charge 750lb

21" Mk 10 - charge 661lb

21" Mk 11 - charge 710lb

18" Mk 12 -charge 388lb

Swordfish carried 18 inch types of torpedoes. The 388lb Mk-12 was typical of the ordinance carried by the type. Late in the war an improved Mk 12 was introduced with a warhead of 545lb TORPEX

Great info. How much did each of these torpedoes weigh? What was the Swordfish max payload? Can the heavier ship launched torpedoes be airdropped, or modified to be airdropped or are aerial torpedoes special?

 

[Nikademus]

Great info. How much did each of these torpedoes weigh? What was the Swordfish max payload? Can the heavier ship launched torpedoes be airdropped, or modified to be airdropped or are aerial torpedoes special?

24.5in Mk 1 = 5700lb

21in Mk 2 = 3100lb (approx)

21in Mk 4 = 3206lb

21in Mk 5 = 3828lb

21in Mk 7 = 4106lb

18in Mk 7 1548lb

18in Mk 8 = ? (prob 1550lb approx)

18in Mk 11 = 1500lb

21in Mk 8 = 3452lb

21in Mk 9 = 3732lb

21in Mk 10 = 3571lb

21in Mk 11 = 3632lb

18in Mk 12 = 1548lb


The swordfish is generally described as being able to lug around 1500lb's of ordinance.